An examination of familial resemblance among subgroups of dyslexics

The goal of the present study was to ascertain whether developmental dyslexics and their affected parents evinced similar patterns of deficits in word recognition skills. Forty dyslexic children and both their biological parents were administered a battery of experimental measures of phonological and orthographic processing. Deficits in component skills were defined in terms of deviations from the performance of normal readers matched on reading achievement level. Four distinct patterns of deficits were found among both the dyslexics and their parents: a subgroup with a specific deficit in processing phonological codes; a subgroup with a specific deficit in processing orthographic codes; a subgroup with deficits in processing both phonological and orthographic codes; and a subgroup of individuals who did not significantly differ from normal readers at the same reading level in either processing domain. Although limited evidence for familial subgroup concordance was obtained in both the phonological and combined phonological subgroups, no concordance was observed among families classified into the orthographic or reading-achievement equivalent subgroups. It was concluded that all affected family members shared a propensity for a phonological deficit, and that some family members share a fundamental problem in processing orthographic information as well. This research was supported by a Biomedical Research Support Grant from the University of Southern California. The research reported in this paper was based on a Ph.D. thesis conducted by the first author at the University of Southern California.     

Phonological awareness,verbal working memory and the acquisition of literacy

This paper describes a 2-year longitudinal study of 76 initially prereading children. The study examined the relationships between phonological awareness (measured by tests of onset and rime, phonemic segmentation and phoneme deletion), verbal working memory and the development of reading and spelling. Factor analyses showed that the verbal working memory tests which were administered loaded on two distinct but highly related factors, the first of which,simple repetition, involved the repetition of verbal items exactly as spoken by the experimenter, whereas the second,backwards repetition, involved repetition of items in reverse order. Factor analyses also showed that, whist the phonological awareness variables consistently loaded on the backwards repetition factor at the beginning and end of Grade 1, by Grade 2 the phonological awareness variables loaded on a separate factor which also included sentence repetition. Results of multiple regression analyses, with reading and spelling as a compound criterion variable, indicated that phonological awareness consistently predicted later reading and spelling even when both simple and backwards repetition were controlled. In contrast, verbal working memory did not consistently predict reading and spelling across testing times. Whilst there was some indication that verbal working memory, especially backwards repetition, measured during Grade 1 did predict reading and spelling in Grade 2, these effects were no longer evident when all three phonological variables were controlled. Nevertheless, with 4 individual reading and 2 individual spelling measures as the criterion variables, it was shown that phonological awareness was not quite such a consistent predictor of reading and spelling: it was most highly related to reading pseudowords and spelling real words; but it was not so highly related to spelling pseudowords, apparently because the processing demands of the task for the young children in the study were extremely high. Given the importance of verbal working memory for the completion of phonological awareness, reading and spelling tasks, in particular for spelling pseudowords, the findings are interpreted as providing some support for a theoretical position which posits that both phonological awareness and verbal working memory contribute to the early stages of literacy acquisition. Whilst the findings suggest some support for a general underlying phonological ability, there is also evidence that, as children learn to read and write, verbal working memory and phonological awareness become more differentiated.     

Genetic and environmental influences on early literacy

Prereading and early reading skills of preschool twin children in Australia, Scandinavia and the United States were explored in a genetically sensitive design (max. N=627 preschool pairs and 422 kindergarten pairs). Analyses indicated a strong genetic influence on preschool phonological awareness, rapid naming and verbal memory. Print awareness, vocabulary and grammar/morphology were subject primarily to shared environment effects. There were significant genetic and shared environment correlations among the preschool traits. Kindergarten reading, phonological awareness and rapid naming were primarily affected by genes, and spelling was equally affected by genes and shared environment. Multivariate analyses revealed genetic and environmental overlap and independence among kindergarten variables. Longitudinal analyses showed genetic continuity as well as change in phonological awareness and rapid naming across the 2 years. Relations among the preschool variables of print awareness, phonological awareness and rapid naming and kindergarten reading were also explored in longitudinal analyses. Educational implications are discussed.     

Name writing but not environmental print recognition is related to letter-sound knowledge and phonological awareness in pre-readers

This paper reports a study exploring the associations between measures of two levels of phonological representation: recognition (epi-linguistic) and production (meta-linguistic) tasks, and very early reading and writing skills. Thirty-eight pre-reading Ottawa-area children, aged 4–5 years, named environmental print (EP), wrote their own name, identified correct names and EP words amongst foils and detected foil letters within EP and names. Results showed that phonological awareness and letter-sound knowledge were not related to EP recognition. Name writing accuracy and name identification were related to both levels of phonological awareness. Furthermore, name writing showed a unique association with phonological awareness even after letter-sound knowledge was controlled statistically. Pre-readers may first use meta-linguistic phonological awareness in their name writing and identification prior to learning to read.     

Naming speed deficits in adults with reading disabilities: a test of the double-deficit hypothesis

The present study investigated the persistent nature of naming speed deficits within the context of the double-deficit hypothesis in a university sample of adults with reading disabilities (RD). Twenty-five university students with RD were compared to 28 typically achieving readers on measures of reading skill, phonological processing, and naming speed. The results indicated that both naming speed and phonological processing deficits characterized the RD group. In a regression analysis, neither naming speed nor phonological processing were important variables in explaining comprehension when reading rate was in the model. The results of the present study are mixed at best and are consistent with earlier conclusions that support for the double-deficit hypothesis of dyslexia remains limited.     

Home activities and cognitive skills in relation to early literacy and numeracy: testing a multifactorial model in preschoolers

The aim of the present study was to test environmental and cognitive variables as possible cross-domain predictors of early literacy and numeracy skills. One hundred forty-eight preschool children (mean age = 64.36 months ± 3.33) were enrolled in the study. The battery included a home literacy and home numeracy questionnaire, measures and phonological and visuo-spatial working memory, tasks tapping response inhibition, and predictors of literacy (vocabulary, phonological awareness, letter knowledge) and numeracy (magnitude comparison, number knowledge) skills. The structural equation model indicated that verbal working memory and, to a lesser extent, inhibition represented cross-domain predictors, whereas home numeracy activities and visuo-spatial working memory explained additional variance only for early numeracy skills. Implications for parents and educators are discussed.

     

Reading skills in early readers: genetic and shared environmental influences

The present study combined parallel data from the Northeast-Northwest Collaborative Adoption Projects (N2CAP) and the Western Reserve Reading Project (WRRP) to examine sibling similarity and quantitative genetic model estimates for measures of reading skills in 272 school-age sibling pairs from three family types (monozygotic twins, dizygotic twins, and unrelated adoptive siblings). The study included measures of letter and word identification, phonological awareness, phonological decoding, rapid automatized naming, and general cognitive ability. Estimates of additive genetic effects and shared environmental effects were moderate and significant. Furthermore, shared environmental effects estimated in twins were generally similar in magnitude to adoptive sibling correlations, suggesting highly replicable estimates across different study designs.     

Growth in early reading skills from kindergarten to third grade

We examined models of individual change and correlates of change in the growth of reading skills in a sample of 40 children from kindergarten through third grade. A broad range of correlates was examined and included family literacy, oral language, emergent reading, intelligence, spelling, and demographic variables. Individual growth curve analysis was used to model change in Letter Word Identification (LWID), Word Attack (WA), and Passage Comprehension (PC) subtests of the Woodcock–Johnson Psychoeducational Battery – Revised. Third grade LWID was predicted uniquely by family literacy, phonological awareness, and emergent reading skills. Growth in LWID was predicted uniquely by emergent reading skills. Phonological awareness, spelling, and emergent reading were unique predictors of third grade WA, whereas family literacy and emergent reading skills uniquely predicted third grade PC. The general oral language factor defined by semantic and syntactic variables did not contribute significant unique variance in any of the models. Thus, the pattern of results extends the model of emergent-to-conventional literacy proposed by Whitehurst and Lonigan (1998) to third grade and suggests that early contextual understandings necessary for competent reading (family literacy and emergent reading) become more influential as reading skills develop.     

Examining the independent contribution of prosodic sensitivity to word reading and spelling in early readers

This study was designed to examine the independent contribution of prosodic sensitivity—the rhythmic patterning of speech—to word reading and spelling in a sample of early readers. Ninety-three English-speaking children aged 5–6 years old (M = 69.28 months, SD = 3.67) were assessed for their prosodic sensitivity, vocabulary knowledge, phonological, and morphological awareness (predictor variables) along with their word reading and spelling (criterion variables). Bivariate (zero-order) correlation analyses revealed that prosodic sensitivity was significantly associated with all other variables in this study. Hierarchical regression analyses revealed that after controlling for individual differences in vocabulary, phonological, and morphological awareness, prosodic sensitivity was still able to explain unique variance in word reading, but was unable to make an independent contribution to spelling. The findings suggest that prosodic sensitivity gives added value to our understanding of children’s reading development.     

Cognitive Endophenotypes of Dyslexia

The study investigated cognitive deficits associated with dyslexia and familial risk of dyslexia (endophenotypes) by comparing children from families with and without a history of dyslexia. Eighty-eight school-aged children were assessed on measures of phonology, language and rapid automatized naming. A series of regression analyses with family risk and dyslexia status as predictors indicated that word recall, morphology, and rapid automatized naming were associated with the deficit, whereas the two phonological measures (phoneme awareness and nonword repetition) were associated with both literacy deficits and family risk, suggesting that the phonological deficit is an endophenotype of dyslexia. Whereas the association with familial risk was similar for the two phonological measures, they differed in their relation to dyslexia status: Phoneme awareness showed a stronger association with dyslexia than risk status, whereas nonword repetition was more strongly related to the risk. The data are interpreted within the framework of multiple deficit models of dyslexia.     

Genetic and Environmental Etiologies of the Longitudinal Relations Between Prereading Skills and Reading

The present study explored the environmental and genetic etiologies of the longitudinal relations between prereading skills and reading and spelling. Twin pairs (n = 489) were assessed before kindergarten (M = 4.9 years), post‐first grade (M = 7.4 years), and post‐fourth grade (M = 10.4 years). Genetic influences on five prereading skills (print knowledge, rapid naming, phonological awareness, vocabulary, and verbal memory) were primarily responsible for relations with word reading and spelling. However, relations with post‐fourth‐grade reading comprehension were due to both genetic and shared environmental influences. Genetic and shared environmental influences that were common among the prereading variables covaried with reading and spelling, as did genetic influences unique to verbal memory (only post‐fourth‐grade comprehension), print knowledge, and rapid naming.     

The role of phonological memory,word recognition,and comprehension skills in reading development: from preschool to grade 2

We examined the relationships among phonologicalawareness, phonological memory, and development ofreading skills in a longitudinal study, by following222 Finnish preschoolers through the grade 2.The main focus was on the role of phonological memoryin word recognition and comprehension. The skillsassessed were verbal abilities, phonological memory,phonological awareness, word recognition, listeningand reading comprehension, altogether comprising themost extensive set of variables so far used in thestudy of phonological memory and reading. We proposeda structural equation model for the developmentalrelationships among the variables. This model waslargely confirmed by the data. The most significantpredictor of word recognition was phonologicalawareness. Phonological memory had only a weak effecton phonological awareness at preschool age, andvia this connection, a weak indirect effect on grade 1 word recognition. Contrary toexpectations, phonological memory also had asignificant, albeit weak effect on grade 2word recognition. Phonological memory did notdirectly affect reading comprehension. However,it was strongly related to listeningcomprehension at preschool, and via the strongeffects of both listening comprehension and wordrecognition on reading comprehension, there weresignificant indirect effects of phonological memory onreading comprehension. The results also underline thestability of development of phonological memory, wordrecognition, and comprehension from preschool to theend of grade 2.     

The importance of letter knowledge in the relationship between phonological awareness and reading

Previous correlational and experimental research has found a positive association between phonological awareness and reading skills. This paper provides an overview of studies in this area and shows that many studies have neglected to control for extraneous variables such as ability, phonological memory, pre‐existing reading skills and letter knowledge. The paper reports on the results of a longitudinal study that took account of these variables when examining the relationship between phonological awareness and reading for a group of children during their first two years at school. Children showed rhyme awareness before they began to read but were unable to perform a phoneme deletion task until after they had developed word‐reading skills. Concurrent and predictive correlations between phonological awareness scores and later reading were often significant and remained so after adjusting for verbal ability or phonological memory. Controlling for letter knowledge, however, reduced most correlations to nonsignificant levels.     

Environmental influences on vocational interest development in adolescents from adoptive and biological families.

Family influences on vocational interest development were studied by hypothesizing that parents with similar interests are more likely to have adolescents who also develop those interests than are parents whose interests are very divergent. In order to unconfound genetic and environmental influences, the 844 parents and adolescent children in 114 biologically related and 101 adoptive families completed the Strong-Campbell Interest Inventory. Parent-child interest difference scores were regressed on parent-parent difference scores (PPDIF), a dummy variable for family type, and the interaction between family type and PPDIF. For all parent-child pairs except mother-son, greater PPDIF scores predicted greater parent-child difference scores (indicating influence of family environment), and there was no family type X PPDIF interaction (indicating that the environmental influence was operating in both biological and adoptive families). Evidence of genetic variance in interest sytyes was also confirmed.     

Early reading development in children at family risk for dyslexia

In a 3-year longitudinal study, middle- to upper-middle-class preschool children at high family risk (HR group, N = 67) and low family risk (LR group, N = 57) for dyslexia (or reading disability, RD), were evaluated yearly from before kindergarten to the end of second grade. Both phonological processing and literacy skills were tested at each of four time points. Consistent with the well-known familiarity of RD, 34% of the HR group compared with 6% of the LR group became RD. Participants who became RD showed deficits in both implicit and explicit phonological processing skills at all four time points, clearly indicating a broader phonological deficit than is often found at older ages. The predictors of literacy skill did not vary by risk group. Both risk groups underwent a similar developmental shift from letter-name knowledge to phoneme awareness as the main predictor of later literacy skill. This shift, however, occurred 2 years later in the HR group. Familial risk was continuous rather than discrete because HR children who did not become RD performed worse than LR non-RD children on some phonological and literacy measures. Finally, later RD could be predicted with moderate accuracy at age 5 years, with the strongest predictor being letter-name knowledge.     

Modeling Phonological Core Deficits Within a Working Memory Architecture in Children and Adults With Developmental Dyslexia

Recent theoretical advances in working memory guided analyses of cognitive measures in 122 children with dyslexia and their 200 affected biological parents in families with a multigenerational history of dyslexia. Both children and adults were most severely impaired, on average, in three working memory components— phonological word-form storage, time-sensitive phonological loop, and executive functions involving phonology. Structural equation modeling showed that, for children, first-order factors from the phonological, orthographic, and/or morphological word forms uniquely predicted 11 reading and writing outcomes but, for adults, a second-order factor (reflecting interrelationships among the three first-order word-form factors) was more likely to be significant in predicting the same reading and writing outcomes. Structural equation modeling of the three working memory component factors showed that the most consistent predictor of text-level reading and writing for both children and adults was the second-order word-form factor. Phonological loop and executive support could be modeled as separate factors in children but only as combined factors in adults. Executive support in children and combined phonological loop and executive support in adults contributed uniquely to oral reading but did not contribute uniquely to reading comprehension or written expression. For both children and adults, individual differences occurred as to which of the three working memory components or three word forms fell outside the normal range.     

Reading and reading-related skills in children using cochlear implants: prospects for the influence of cued speech

We assessed the reading and reading-related skills (phonemic awareness and phonological short-term memory) of deaf children fitted with cochlear implants (CI), either exposed to cued speech early (before 2 years old) (CS+) or never (CS-). Their performance was compared to that of 2 hearing control groups, 1 matched for reading level (RL), and 1 matched for chronological age (CA). Phonemic awareness and phonological short-term memory were assessed respectively through a phonemic similarity judgment task and through a word span task measuring phonological similarity effects. To assess the use of sublexical and lexical reading procedures, children read pseudowords and irregular words aloud. Results showed that cued speech improved performance on both the phonemic awareness and the reading tasks but not on the phonological short-term memory task. In phonemic awareness and reading, CS+ children obtained accuracy and rapidity scores similar to CA controls, whereas CS- children obtained lower scores than hearing controls. Nevertheless, in phonological short-term memory task, the phonological similarity effect of both CI groups was similar. Overall, these results support the use of cued speech to improve phonemic awareness and reading skills in CI children.     

Development of Reading in Grades K–2 in Spanish‐Speaking English‐Language Learners

Development of English‐ and Spanish‐reading skills was explored in a sample of 251 Spanish‐speaking English‐language learners from kindergarten through Grade 2. Word identification and reading comprehension developed at a normal rate based on monolingual norms for Spanish‐ and English‐speaking children, but English oral language lagged significantly behind. Four categories of predictor variables were obtained in Spanish in kindergarten and in English in first grade: print knowledge, expressive language (as measured by vocabulary and sentence repetition tasks), phonological awareness, and rapid automatic naming (RAN). Longitudinal regression analyses indicated a modest amount of cross‐language transfer from Spanish to English. Hierarchical regression analyses indicated that developing English‐language skills (particularly phonological awareness and RAN) mediated the contribution of Spanish‐language variables to later reading. Further analyses revealed stronger within‐ than cross‐language associations of expressive language with later reading, suggesting that some variables function cross‐linguistically, and others within a particular language. Results suggest that some of the cognitive factors underlying reading disabilities in monolingual children (e.g., phonological awareness and RAN) may be important to an understanding of reading difficulties in bilingual children.     

The influence of speech perception,oral language ability,the home literacy environment,and pre-reading knowledge on the growth of phonological sensitivity: A one-year longitudinal investigation

Individual differences in phonologicalsensitivity are among the most powerfulpredictors of early word decoding ability and adeficit in phonological sensitivity is thoughtto be the primary stumbling block for thosechildren who have difficulty learning to read. However, only recently have researchers begunto search for the potential causes andcorrelates in phonological sensitivitydevelopment. In the present one-yearlongitudinal study, the influences of speechperception, oral language ability, emergentliteracy, and the home literacy environment(HLE) on the growth of phonological sensitivitywere examined in a group of 115 four- andfive-year-old children. When the variables wereentered simultaneously into a multipleregression equation, emergent literacy, orallanguage, and the HLE contributed significantunique variance. However, when theautoregressor was controlled, only phonologicalsensitivity at Time 1 and HLE contributedsignificant unique variance to predictinggrowth in phonological sensitivity. Resultsare discussed in terms of their implicationsfor the education of preschool as well asschool-aged children.     

Understanding the relations between RAN letter subtest components and word reading in first-grade students

First-grade students (N = 221) were individually tested on a battery of cognitive and achievement measures of verbal fluency, visual attention, phonological awareness, orthographic recognition, rapid automatized naming (RAN) of letters and objects, and reading. All tests were subjected to postacquisition scoring, and all RAN measures were segregated into measures of articulation time, pause time, and consistency of the pause time. Structural equation modeling demonstrated that word reading was directly and significantly predicted by RAN letter naming and general RAN cognitive processing time of objects. Moreover, RAN letter reading constructs were significantly and directly predicted by the latent variables of phonological awareness, orthographic recognition, and general RAN object articulation and cognitive processing times. RAN letter naming constructs were also significantly and indirectly predicted by visual attention. The reading model was found to be consistent with a total mediation of the relation of phonological awareness and reading through RAN letter naming and supported the validity of the RAN letter naming subtest as a basic letter reading test. These findings supported the double-deficit hypothesis for letter reading. We suggest that phonological memory is a basic factor underlying general RAN cognitive processing time of objects and domain-specific information associated with phonemes and their graphic representations.